Re: booting btrfs

[Chris Murphy]

On Dec 22, 2013, at 10:32 PM, Chris Murphy <address@hidden> wrote:
> 
> If relative paths are used, neither core.img nor grub.cfg needs to be 
> modified, because merely a user space program changing the default subvolume 
> would cause the existing core.img and grub.cfg to boot the snapshot.

This seems wrong on second thought. The grub.cfg boot param 
rootflags=subvol=<path> is interpreted by the kernel, not grub. And for Btrfs 
subvolume paths are always absolute. Same as fstab.

In that case, getting grub to do paths relative to the default subvolume only 
helps core.img point to the desired snapshot where /boot/grub/grub.cfg is 
located. The alternative is to write out a new core.img. Another is to ensure 
/boot is not being snapshot. So we should be clear on the benefits of 
snapshotting /boot vs the added complexity.


Chris Murphy